Piet, J., Würtzen, H., & Zachariae, R. (2012). The effect of mindfulness-based therapy on symptoms of anxiety and depression in adult cancer patients and survivors: A systematic review and meta-analysis. Journal of Consulting and Clinical Psychology, 80, 1007–1020.

To evaluate current evidence regarding the effect of mindfulness-based therapy (MBT) on symptoms of anxiety and depression in patients with cancer

• Databases used in the search were EMBASE, PubMed, PsycINFO, Web of Science, Scopus, and Cochrane Collaboration.
• Search keywords were mindfulness, MBT, MBSR, and cancer.
• Inclusion criteria were English-language studies reporting on adult patients with a current or former diagnosis of cancer who were receiving MBT or mindfulness-based stress reduction (MBSR) as an intervention. Studies included pre- and postintervention valid continuous measures of anxiety or depression symptoms.
• Exclusion criteria were unspecified.

• The study included 670 references.
• Authors used the Jadad scale to evaluate and comment on the literature.

• A final number of 22 studies were included in the review.   
• Sample range across studies was 1,409 participants, with a range of 12–287.
• Mean participant age was 55 years.
• Women with breast cancer represented 86% of the sample.

Multiple phases of care

Among nonrandomized studies, overall effect size for anxiety was 0.60 (Hedges’s g, p < 0.001) and 0.42 (p < 0.001) for depression. Among randomized controlled trials, effect size for anxiety was 0.37 and 0.44 (p < 0.001) for depression. Most studies used the Profile of Mood States scale or the State-Trait Anxiety Inventory. The range of Jadad quality scores was 0–4, with only six studies having scores greater than 2. This score indicates low quality. Heterogeneity among studies was moderate.

Findings demonstrate a low to moderately significant effect of MBT in reducing anxiety and symptoms of depression among patients with cancer. Heterogeneity among studies suggests that findings be viewed with caution.

• Most participants were women with breast cancer. Findings may not be generalizable to males and to other diseases.
• The quality of many of the assessed studies was low. 
• Most studies did not include patients with clinically significant levels of anxiety or depression at baseline.
• Studies were done at various phases in the cancer trajectory, so how the phase of care may have influenced findings is unclear. 
• In general, anxiety and depression symptoms improve over time with no intervention. The research did not consider this fact.

MBT may benefit patients with cancer by reducing anxiety and symptoms of depression. The use of MBT appears to be feasible in cancer care. The low quality of studies in this analysis points to the need for well-designed research on the effects of MBT.